Gas Turbines for Missile Ground Support

Abstract

HANDLING, testing, and launching of guided missiles require a multitude of services which are external to the missile proper. Specific requirements for such ground support equipment are dictated by the operational concept of the missile system and the detail design of the missile. In general, hydraulic, electric, mechanical, and pneumatic power are needed at the site of operation for erecting and aligning, fueling, calibration, checkout, and launching. The proper selection of the prime movers for such services is of great importance, considering the safety, reliability, quality, and control requirements. In addition, depending on the operational concepts, emphasis may be placed on such items as versatility, transportability, self-sufficiency, and logistics. Considering these, the advantage of using gas turbine prime movers is definitely indicated. The lightweight, compact engines are capable of using a wide variety of fuels and are easy to integrate with the driven components, such as pumps, compressors, and generators. Solar Aircraft Company has designed and is manufacturing a variety of gas turbine driven power units for diverse applications. Solar combines them in complete packages for ground, shipboard, and airborne electric generator sets, space heaters, smoke generators, air bleed power supplies, and pumps. The present production units use as the prime movers the 50-hp Mars and the 500-hp Jupiter engines. The Mars engine weighs approximately 100 lb, which includes the gearbox and the accessories, and its dimensions are 23 in. in height, 17 in. in width, and 23 in. in length. I t develops 50 bhp at a speed of 40,000 rpm, or 42 ppm bleed air with a bleed air pressure of 18.3 psig. Air mass flow, pressure ratio, and fuel consumption are 2.7 pps, 2.5:1, and 2.2 lb/bhp X hr, respectively. The Jupiter engine weighs approximately 990 lb, including gearbox and accessories; its dimensions are 42 in. by 32 in. by 91 in. I t develops up to 520 bhp at 20,000 rpm, or 150 ppm bleed air with a pressure of 45 psig. Air mass flow, pressure ratio, and fuel consumption are 9 pps, 4.6:1, and 0.92 lb/bhp X hr, respectively. Both engines are designed for operation over a temperature range from — 65 F to + 130 F. They operate on all commonly used fuels, such as gasoline, jet engine fuel, diesel fuel, and kerosene. Complete protection against overspeed, overtemperature, and loss of oil pressure is provided. Construction of both engines is simple and compact. The Mars engine employs a single-stage centrifugal compressor, single elbow combustor, and a singlestage radial inflow turbine. Turbine and compressor are mounted back-to-back on the same shaft. The Jupiter engine employs a ten-stage axial compressor, single combustor, and a three-stage axial turbine. For constant speed application, the three stages are coupled together, whereas for variable speed application the third stage of the turbine is not connected to the gas producer section but mounted on a separate power take-off shaft. Both engines have completely automatic electrical start systems, and power is available in less than one minute even at extreme low temperatures. Preheating is not required. The Mars engine is also available with a hand-crank starting system; the Jupiter engine is adaptable for pneumatic or fuel-air starting systems. Standard speed control systems for both engines incorporate a droop-type governor with 5 per cent droop from no load to full load and steady-state speed variation of ± 0 . 5 per cent. The system is adaptable for isochronous governing and parallel operation w^hen used for generator set applications. Other types and sizes of gas turbine prime movers are presently in development to satisfy power requirements different from those of the described units. I t is important that proper and timely consideration be given to the ground support requirements for guided missiles systerns so that optimization of the system be achieved, and an effective research tool or weapon be developed. The gas turbine prime mover should play a more important role in this concept in the future, due to its inherent characteristics and flexibility for integration into such a complex system.